An improved integral equation formulation for analysis of scattering from composite conducting and dielectric objects

The surface integral equation (SIE) method is one of the most powerful numerical method in the electromagnetic analysis of objects composed of conducting and piecewise homogeneous dielectric regions. CFIE-PMCHW equation is often applied for computing scattering by composite object if the metallic surface is closed, where CFIE is applied on the metallic surface and PMCHW on dielectric interface. If metallic region is an open or sharp structure, only EFIE equation is valid for the surface. Unfortunately discretization of EFIE-PMCHW equation leads to a matrix equation with a high condition number, which deteriorates the convergence of iterative method and affects the solution accuracy. Recently an improved EFIE (IEFIE) is proposed to accelerate the iteration solution of EFIE for conducting object. By adding the principal value term of the MFIE operator into the EFIE operator, a well-conditioned IEFIE is constructed. In this paper, an improved PMCHW (IPMCHW) formulation applied on dielectric interface combined with IEFIE is proposed to improve the convergence rate of EFIE- PMCHW. A two-level iterative technique is developed to assure the accuracy of IEFIE-IPMCHW. Numerical examples have been given to show validity, accuracy and efficiency of this method.